bridges: Fix default return values and function scopes

getURI and getName should fall back to parent::getURI or
parent::getName respectively if it cannot build propper
return values.

Functions defined by bridges should be made private to
prevent confusion with inherited functions

bridges/DailymotionBridge.php

@@ -34,7 +34,7 @@ class DailymotionBridge extends BridgeAbstract{
             )
         );
 
-    function getMetadata($id) {
+    protected function getMetadata($id) {
         $metadata=array();
         $html2 = getSimpleHTMLDOM(self::URI.'video/'.$id);
         if(!$html2){